Red List for Aquatic Invertebrates Status Definitions

PE — Possibly Extinct: Missing; known from only historical occurrences, but still some hope of rediscovery.

CI — Critically Imperiled: At very high risk of extinction due to extreme rarity (often 5 or fewer populations), very steep declines, or other factors.

I — Imperiled: At high risk of extinction due to very restricted range, very few populations (often 20 or fewer), steep declines, or other factors.

V — Vulnerable: At moderate risk of extinction due to a restricted range, relatively few populations (often 80 or fewer), recent and widespread declines, or other factors.

DD — Data Deficient: Inadequate information to make an assessment of its risk category, either through lack of knowledge of population size, threats to it, or to taxonomic uncertainty of the validity of the taxon.